The Psychosocial Measures Core will provide a coordinated and integrated framework for the self-reported assessment of socio-demographic, behavioral,psychological, social, and experiential factors that will be used in the various MIDUS projects to investigate life course variations in health and illness. These measureswill be used, along with additional data, in Projects 2 - 5. The measures consist of a 45-minute telephone interview and a 100page self-administered questionnaire. Most of the measures were included in the first wave of the MIDUS data collection (MIDUS I), with additional measures proposed for this second wave. Thus, these measures provide the operational integration of the projects that constitute this P01and the mechanism by which the proposed research can be linked longitudinally with the first round of MIDUS data. The MIDUS II psychosocial measures are organized into six primary domains: (1) sociodemographic factors, (2) psychological factors, (3) social factors, (4) life challenges, (5) health behaviors, and (6) self-reported mental and physical health. The first five of these are conceptualized as a diverse array of risk or protective factors that have been shown in past research to influencethe sixth domain, self-reported physical and mental health. Within each of these, we utilize state of the art measurement instruments that build on and extend the research programs of the P01 projects. Multiple indicators of each domain are used to facilitate modeling.